[xine-devel] Simultaneous Digital Passthrough and Stereo Analog
Audio

Please bear with me I am new to OSS devel groups... And very new to the
Xine source code.
I do not have a patch to post yet. I am sending this email to field
ideas for approaches from the group.
I am working with a group developing a CE product that uses xine-lib.
Because we are a CE product when playing an AC3 encoded audio track we
need to simultaneously output a stereo (Prologic) analog audio from the
L and R outputs, plus pass through the AC3 stream via the SPDIF output.
I have looked through the mailing list and the only approach I see
mentioned is to decode to 5.1 and re-encode using the alsa ac3 encoder
plugin. Unfortunately that approach is not acceptable for our product.
It would be better if the SPDIF output was passed through untouched.
The sound hardware is Intel HDA based, so it has no problem doing this
if both the Digital and Analog devices are appropriately opened.
The problem I have is with the stream architecture of Xine. Since it
lacks a Pre-Plugin api there is currently no way to "T" the pre-decode
stream before the A52 decoder.
One idea kicked around has been to use a pass through decoder plugin,
and then use a T and the A52 decoder as post plugins.
Does anyone have any ideas how we should go about this? Any
recommendations?
----------------------------------------------------
Bob Bouterse

Thread view

Please bear with me I am new to OSS devel groups... And very new to the
Xine source code.
I do not have a patch to post yet. I am sending this email to field
ideas for approaches from the group.
I am working with a group developing a CE product that uses xine-lib.
Because we are a CE product when playing an AC3 encoded audio track we
need to simultaneously output a stereo (Prologic) analog audio from the
L and R outputs, plus pass through the AC3 stream via the SPDIF output.
I have looked through the mailing list and the only approach I see
mentioned is to decode to 5.1 and re-encode using the alsa ac3 encoder
plugin. Unfortunately that approach is not acceptable for our product.
It would be better if the SPDIF output was passed through untouched.
The sound hardware is Intel HDA based, so it has no problem doing this
if both the Digital and Analog devices are appropriately opened.
The problem I have is with the stream architecture of Xine. Since it
lacks a Pre-Plugin api there is currently no way to "T" the pre-decode
stream before the A52 decoder.
One idea kicked around has been to use a pass through decoder plugin,
and then use a T and the A52 decoder as post plugins.
Does anyone have any ideas how we should go about this? Any
recommendations?
----------------------------------------------------
Bob Bouterse

Bouterse, Bob wrote:
>
> Please bear with me I am new to OSS devel groups... And very new to
> the Xine source code.
>
>
>
> I do not have a patch to post yet. I am sending this email to field
> ideas for approaches from the group.
>
>
>
> I am working with a group developing a CE product that uses xine-lib.
> Because we are a CE product when playing an AC3 encoded audio track we
> need to simultaneously output a stereo (Prologic) analog audio from
> the L and R outputs, plus pass through the AC3 stream via the SPDIF
> output.
>
There is some similar stuff done in the Mythtv project. See the
"multichannel audio" posts and patches which are not yet in the main
codebase. There is a bug report collecting patches I think
You could also look at Jack and perhaps pulseaudio as another route?
Good luck
Ed W

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